* 1993 Spectrum and 1995 US Polydor are clones of this disc
** 1999 US Polydor is a clone of this disc
*** The 30th anniversary edition (Polar 2004) audio CD uses the same mastering as this disc

There have been five distinct masterings of Waterloo on CD. The album was one of the final original Abba albums to appear on the format, making its debut as a Swedish only release on Polar in 1988.

Both the 1988 Polar and 1992 Polydor are flat, 'warts and all'
transfers of whatever tape the record labels had to hand. The Polar version was probably taken from the album's Swedish LP master while the Polydor version used a copy tape sent to West Germany for LP cutting in the 1970s.

Both editions reveal the flaws of their source tapes. The 1988 Polar can be muddy at times [particularly on Suzy-Hang-Around and Honey, Honey] while the 1992 Polydor is brighter, somewhat noiser and has harsher equalisation.

The first remastered version of the album came in 1997 when all the original Abba albums were remastered by Jon Astley and Michael B Tretow at Abbey Road, London.

Astley compressed the sound to reduce its dynamic range, hence allowing him to make it louder. He also applied heavy noise reduction [probably using the CEDAR system] and altered the original equalisation to suit his tastes.

When the remasters were reissued in 2001, Astley added more noise reduction processing and altered the equalisation again, resulting in somewhat better results, particularly amongst the album's lower frequencies.

Both Astley remasters, however, are highly controversal amongst audiophiles due to the level of noise reduction and compression used.
Many feel his work deadened the sound, with a few even suspecting that he had remixed the albums as his remasters sounded so different to previous editions.

In 2005, the album was revisited again as part of the Complete Recordings Boxset. Henrik Jonsson of Masters of Audio, Stockholm, did the remastering this time, with mixed results.

Jonsson somehow produced a remaster that was louder than the Astley remasters but didn't seem to compromise the dynamic range as much. He also didn't use any noise reduction. Some sensible equalisation work also revealed previously unheard details in the music but, for many audiophiles, this was spoilt by the sheer loudness of the remaster and dynamic range compromises taken.

The verdict:
Best sounding: 1988 Polar [meets all audiophile criteria but with no restoration work]
2nd: 2005 CSR version [loud but impressive; not audiophile by any stretch of the imagination though]
3rd: 1992 Polydor [harsh Eqing but contains the best versions of a few tracks]

Individual track by track:
If you wanted to compile the best sounding version of Waterloo, you will have to use several CDs. The 1988 Polar is perfect for most tracks but a couple of the muddier sounding tracks will need to be sourced from elsewhere.

Although I have recommended Honey, Honey from the revered in audiophile circles Atlantic Greatest Hits Vol CD, the version from the
1992 Polydor is a perfectly adequate and cheaper option.